Most precise fraction display method

• US 5,155,697 A
• Filed: 01/31/1991
• Issued: 10/13/1992
• Est. Priority Date: 01/31/1991
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Company (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Bunsen, Chris M.
• Primary Examiner(s): NGUYEN, LONG
• Application Number:
  US07/648,120
• Time in Patent Office: 621 Days
• Field of Search: 364/709.01, 364/709.07
• US Class Current: 708/137
• CPC Class Codes: G06F 15/02 manually operated with input through keyboard and computation using a built-in program, e.g. pocket calculators
• CPC Class Codes: G06F 17/10 Complex mathematical operations function generation by table look-up G06F1/03; evaluation of elementary functions by calculation G06F7/544
• CPC Class Codes: G06F 7/4836 Computations with rational numbers
• CPC Class Codes: G06F 7/60 Methods or arrangements for performing computations using a digital non-denominational number representation, i.e. number representation without radix; Computing devices using combinations of denominational and non-denominational quantity representations , e.g. using difunction pulse trains, STEELE computers, phase computers conversion of digital data to or from non-denominational form H03M5/00, H03M7/00

Abstract

In a calculating device, a method for calculating a fraction that most accurately represents a related decimal value stored within the device. The user may select a maximum denominator value to limit the amount of calculation involved.

Claims

1. A calculator comprising

(a) a display;

(b) a keyboard having a plurality of keys for entering numeric values, for entering a maximum denominator and for initiating calculation of a fractional representation of an entered numeric value; and

(c) a processor for;

storing, upon activation by a user of a function key on the keyboard, a value entered into the calculator as the maximum denominator for a frictional representation;

displaying on the display a numeric value entered into the calculator for which a fractional representation is desired;

calculating, upon activation by a user of a function key on the keyboard, a most precise fractional representation of the entered numeric value in which the denominator of the fractional representation does not exceed the maximum entered denominator; and

displaying the fractional representation of the entered numeric value.

2. The calculator of claim 1 wherein the function key for entering the maximum denominator and for initiating calculation of the most precise fractional representation are the same key.

3. The calculator of claim 1 wherein the fractional representation and the entered numeric value are different values, the entered numeric value being unaffected by the fractional representation thereof.

4. The calculator of claim 1 wherein the entered numeric value for which a fractional representation is desired is a decimal value.

5. In a calculator, a method of displaying a fractional representation, within a preselected range of denominators, of an entered numeric value, comprising

pressing a key for recognizing a value entered into the calculator as a maximum denominator for a fractional representation;

displaying a numeric value entered into the calculator for which a fractional representation is desired;

pressing a key for initiating the calculation of a most precise fractional representation of the entered numeric value in which the denominator of the fractional representation does not exceed the maximum denominator; and

displaying, in response to pressing of the initiating key, the fractional representation of the entered numeric value.

6. The method of claim 5, wherein the calculation of the fractional representation of the entered numeric value comprises:

deriving a fractional representation of the numeric value with continued fractions; and

comparing the denominator of the fractional representation after each subcalculation to the maximum denominator to determine if the denominator of the fractional representation exceeds the maximum denominator.

7. In a calculator, a method of displaying a fractional representation of a stored numeric value, comprising:

providing a key for entering a selected maximum denominator for the fractional representation;

providing a key for initiating calculation of the fractional representation;

entering a value as the maximum desired denominator;

pressing the entering key to recognize the entered value as the maximum desired denominator;

entering a numeric value for which a fractional representation is desired;

pressing the initiating key to calculate with continued fractions a fractional representation of the numeric value, the calculation including comparing after each subcalculation the fractional representation against the maximum desired denominator to ensure that the denominator of fractional representation does not exceed the maximum denominator; and

displaying the fractional representation of the entered numeric value.

8. The method of claim 7 wherein the entering key and initiating key are the same key.